U.S. patent number 11,228,952 [Application Number 16/303,954] was granted by the patent office on 2022-01-18 for method and apparatus for low-power operations of terminal and base station in mobile communication system.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Rayeon Ahn, Jiwon Hwang, Jungsoo Jung, Sungjin Lee, Sunheui Ryoo.
United States Patent |
11,228,952 |
Ryoo , et al. |
January 18, 2022 |
Method and apparatus for low-power operations of terminal and base
station in mobile communication system
Abstract
The present disclosure relates to a communication technique for
converging IoT technology with a 5G communication system for
supporting a higher data transfer rate beyond a 4G system, and a
system therefor. The present disclosure can be applied to
intelligent services (e.g., smart homes, smart buildings, smart
cities, smart or connected cars, health care, digital education,
retail business, and services associated with security and safety)
on the basis of 5G communication technology and IoT-related
technology.
Inventors: |
Ryoo; Sunheui (Yongin-si,
KR), Jung; Jungsoo (Seongnam-si, KR), Lee;
Sungjin (Bucheon-si, KR), Ahn; Rayeon (Seoul,
KR), Hwang; Jiwon (Suwon-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
N/A |
KR |
|
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Assignee: |
Samsung Electronics Co., Ltd.
(Suwon-si, KR)
|
Family
ID: |
60412328 |
Appl.
No.: |
16/303,954 |
Filed: |
May 24, 2017 |
PCT
Filed: |
May 24, 2017 |
PCT No.: |
PCT/KR2017/005364 |
371(c)(1),(2),(4) Date: |
November 21, 2018 |
PCT
Pub. No.: |
WO2017/204539 |
PCT
Pub. Date: |
November 30, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200322854 A1 |
Oct 8, 2020 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62340757 |
May 24, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
76/34 (20180201); H04W 48/18 (20130101); H04W
76/27 (20180201); H04W 76/16 (20180201); H04W
36/0088 (20130101); H04W 68/12 (20130101); H04W
36/0058 (20180801); H04W 36/0085 (20180801); H04W
36/0069 (20180801); H04W 76/30 (20180201); H04W
48/16 (20130101); Y02D 30/70 (20200801); H04W
88/06 (20130101); H04W 84/18 (20130101) |
Current International
Class: |
H04W
36/00 (20090101); H04W 76/27 (20180101); H04W
76/30 (20180101); H04W 84/18 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2014-0005149 |
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Jan 2014 |
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KR |
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2014/182772 |
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Nov 2014 |
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WO |
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2015/026316 |
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Feb 2015 |
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WO |
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2016/049431 |
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Mar 2016 |
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WO |
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2016/056968 |
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Apr 2016 |
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WO |
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Other References
European Search Report dated Apr. 12, 2019, issued in European
Patent Application No. 17803058.1. cited by applicant .
Indian Office Action dated Sep. 6, 2021, issued in Indian Office
Action 201837043829. cited by applicant.
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Primary Examiner: Thompson, Jr.; Otis L
Attorney, Agent or Firm: Jefferson IP Law, LLP
Claims
The invention claimed is:
1. A method of transmitting and receiving a signal performed by a
terminal in a wireless communication system, the method comprising:
receiving, from a first base station, system information including
an indication used for determining that the terminal entered a
coverage area of a second base station, wherein the first base
station operates based on a first radio access technology (RAT),
and the second base station operates based on a second RAT;
receiving, from the first base station, a radio resource control
(RRC) connection reconfiguration message including measurement
configuration information for a cell of the second base station;
performing a measurement for the cell of the second base station
using first information identifying a carrier frequency of the
second RAT for the measurement and second information for
identifying a threshold of the second RAT, based on the measurement
configuration information; and transmitting, to the first base
station, a result of the measurement for the cell of the second
base station.
2. The method of claim 1, further comprising: determining that the
second base station exists within a coverage of the first base
station based on the indication.
3. The method of claim 1, further comprising receiving, from the
first base station, a message adding the cell of the second base
station as a secondary cell group for the terminal, based on the
result of the measurement.
4. The method of claim 3, wherein the first RAT is long term
evolution (LTE) and the second RAT is new radio (NR), and wherein
the first base station operates as a master node (MN) for the
terminal, and the second base station operates as a secondary node
(SN) for the terminal, based on a dual connectivity.
5. A method of transmitting and receiving a signal performed by a
first base station in a wireless communication system, the method
comprising: transmitting, to a terminal, system information
including an indication used for determining that the terminal
entered a coverage area of a second base station,. wherein the
first base station operates based on a first radio access
technology (RAT), and the second base station operates based on a
second RAT; transmitting, to the terminal, a radio resource control
(RRC) connection reconfiguration message including measurement
configuration information for a cell of the second base station,
first information for identifying a carrier frequency of the second
RAT for a measurement and second information for identifying a
threshold of the second RAT for the measurement being based on the
measurement configuration information; and receiving, from the
terminal, a result of the measurement for the cell of the second
base station based on the first information and the second
information.
6. The method of claim 5, wherein the terminal determines that the
second base station exists within a coverage of the first base
station based on the indication.
7. The method of claim 5, further comprising transmitting, to the
terminal, a message adding the cell of the second base station as a
secondary cell group for the terminal, based on the result of the
measurement.
8. The method of claim 7, wherein the first RAT is long term
evolution (LTE) and the second RAT is new radio (NR), and wherein
the first base station operates as a master node (MN) for the
terminal, and the second base station operates as a secondary node
(SN) for the terminal, based on a dual connectivity.
9. A terminal for transmitting and receiving a signal in a wireless
communication system, the terminal comprising: a transceiver
configured to transmit and receive the signal; and a controller
coupled with the transceiver and configured to: receive, from a
first base station, system information including an indication used
for determining that the terminal entered a coverage area of a
second base station, wherein the first base station operates based
on a first radio access technology (RAT), and the second base
station operates based on a second RAT, receive, from the first
base station, a radio resource control (RRC) connection
reconfiguration message including measurement configuration
information for a cell of the second base station, perform a
measurement for the cell of the second base station using first
information identifying a carrier frequency of the second RAT for
the measurement and second information for identifying a threshold
of the second RAT, based on the measurement configuration
information, and transmit, to the first base station, a result of
the measurement for the cell of the second base station.
10. The terminal of claim 9, wherein the controller is further
configured to determine that the second base station exists within
a coverage of the first base station based on the indication.
11. The terminal of claim 9, wherein the controller is further
configured to receive, from the first base station, a message
adding the cell of the second base station as a secondary cell
group for the terminal, based on the result of the measurement.
12. The terminal of claim 11, wherein the first RAT is long term
evolution (LTE) and the second RAT is new radio (NR), and wherein
the first base station operates as a master node (MN) for the
terminal, and the second base station operates as a secondary node
(SN) for the terminal, based on a dual connectivity.
13. A first base station for transmitting and receiving a signal in
a wireless communication system, the first base station comprising:
a transceiver configured to transmit and receive the signal; and a
controller coupled with the transceiver and configured to:
transmit, to a terminal, system information including an indication
used for determining that the terminal entered a coverage area of a
second base station, wherein the first base station operates based
on a first radio access technology (RAT), and the second base
station operates based on a second RAT, transmit, to the terminal,
a radio resource control (RRC) connection reconfiguration message
including measurement configuration information for a cell of the
second base station, first information for identifying a carrier
frequency of the second RAT for a measurement and second
information for identifying a threshold of the second RAT for the
measurement being based on the measurement configuration
information, and receive, from the terminal, a result of the
measurement for the cell of the second base station based on the
first information and the second information.
14. The first base station of claim 13, wherein the terminal
determines that the second base station exists within a coverage of
the first base station based on the indication.
15. The first base station of claim 13, wherein the controller is
further configured to transmit, to the terminal, a message adding
the cell of the second base station as a secondary cell group for
the terminal, based on the result of the measurement.
16. The first base station of claim 15, wherein the first RAT is
long term evolution (LTE) and the second RAT is new radio (NR), and
wherein the first base station operates as a master node (MN) for
the terminal, and the second base station operates as a secondary
node (SN) for the terminal, based on a dual connectivity.
Description
TECHNICAL FIELD
The present disclosure relates to a communication system and, more
particularly, to a method and apparatus for reducing a control
burden on a network, power consumption and consumption power of a
user equipment.
BACKGROUND ART
In order to satisfy a wireless data traffic demand that tends to
increases after the 4G communication system commercialization,
efforts to develop an improved 5G communication system or pre-5G
communication system is being made. For this reason, the 5G
communication system or pre-5G communication system is called a
beyond 4G network communication system or a post LTE system.
In order to achieve a high data transfer rate, the 5G communication
system is considered to be implemented in an mmWave band (e.g., 60
GHz band). In order to reduce a loss of electric waves and increase
the transfer distance of electric waves in the mmWave band,
beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), array
antenna, analog beam-forming and large scale antenna technologies
are being discussed in the 5G communication system.
Furthermore, in order to improve the network of a system,
technologies, such as an improved small cell, an advanced small
cell, a cloud radio access network (cloud RAN), an ultra-dense
network, device to device communication (D2D), wireless backhaul, a
moving network, cooperative communication, coordinated multi-points
(CoMP) and reception interference cancellation, are being developed
in the 5G communication system.
In addition, hybrid FSK and QAM modulation (FQAM) and sliding
window superposition coding (SWSC) that are advanced coding
modulation (ACM) schemes, improved filter bank multi-carrier
(FBMC), non-orthogonal multiple access (NOMA) and sparse code
multiple access (SCMA) are being developed in the 5G system.
Meanwhile, the Internet evolves from a human-centered connection
network over which human generates and consumes information to
Internet of Things (IoT) in which information is exchanged and
process between distributed elements, such as things. An Internet
of Everything (IoE) technology in which a big data processing
technology through a connection with a cloud server is combined
with the IoT technology is emerging. In order to implement the IoT,
technical elements, such as the sensing technology, wired/wireless
communication and network infrastructure, service interface
technology and security technology, are required. Accordingly,
technologies, such as a sensor network, machine to machine (M2M)
and machine type communication (MTC) for a connection between
things, are recently researched. In the IoT environment, an
intelligent Internet technology (IT) service in which a new value
is created for human life by collecting and analyzing data
generated from connected things may be provided. The IoT may be
applied to fields, such as a smart home, a smart building, a smart
city, a smart car or a connected car, a smart grid, health care,
smart home appliances, and advanced medical services, through
convergence and composition between the existing information
technology (IT) and various industries.
Accordingly, various attempts to apply the 5G communication system
to the IoT are being made. For example, 5G communication
technologies, such as a sensor network, machine to machine (M2M)
and machine type communication (MTC), are implemented by schemes,
such as beamforming, MIMO, and an array antenna. The application of
a cloud wireless access network (cloud RAN) as the aforementioned
big data processing technology may be said to be an example of
convergence between the 5G technology and the IoT technology.
Meanwhile, a radio resource control (RRC) state in which a wireless
communication terminal transmits and receives data has been
conservatively designed based on a previous generation
communication system based on a voice call. For example, a terminal
has severe power consumption because it maintains the standby time
(e.g., Connected DRX) in the RRC connected state although there is
no traffic arrival for a given time after traffic reception.
Furthermore, in the case of a smartphone user, data, such as a keep
alive message not related to user quality of service (QoS),
frequently occurs. If an RRC connection therefor is maintained as
at the present, terminal power consumption may become further
deteriorated.
DISCLOSURE OF INVENTION
Technical Problem
In the same/similar frequency band environment in a band of 6 GHz
or less, if dual connectivity in which a macrocell and a small cell
operate is applied to 5G without any change, an inefficiency
problem becomes further great in the power consumption aspect. A
terminal performs communication with a macrocell and a small cell
by consecutively performing measurement on the macrocell and the
small cell and activating a plurality of modems in the RRC
connected state through the dual connectivity technology. This may
result in a problem in that power consumption of a terminal is
deepened when taking into consideration power consumption in the
mmWave beamforming environment of a high frequency band.
Accordingly, in order to solve the aforementioned problems, in the
present disclosure, an RRC Idle interval is extended and user
equipment power efficiency is improved by minimizing the RRC
connected state for a 5G cell through CP tail minimization control
of a base station.
Furthermore, in the present disclosure, a 5G cell link activation
state (RRC Connected state and measurement execution) of a user
equipment is minimized, and QoS (specifically, latency criterion)
of a user is also satisfied. Moreover, in the present disclosure,
network (N/W) signaling overhead and power consumption of a user
equipment, additionally occurring due to frequent transition from
the RRC Idle state to the RRC connected state although a user
equipment enters the RRC Idle state in the early stage due to a CP
tail reduction, are minimized.
Solution to Problem
In order to solve the above problem, a method of a user equipment
supporting a first radio access technology (RAT) and a second RAT
in a mobile communication system includes detecting whether a
condition for activating a second connection based the second RAT
is satisfied through a first connection based the first RAT and
releasing the second connection when the transmission and reception
of traffic through the second connection is completed and a timer
configured with respect to the second connection expires. The timer
for the second connection and a timer for the first connection are
differently configured.
In accordance with an embodiment of the present disclosure, the
condition for activating the second connection may be determined
based on the capacity of a buffer for data to be transmitted and
received by the user equipment, and the timer for the second
connection may be configured to be shorter than the timer for the
first connection.
In accordance with an embodiment of the present disclosure, the
method further includes performing measurement on the second
connection prior to the detecting. The measurement may be performed
based on at least one of whether the user equipment is present in
coverage of the second connection, information about a service to
be provided through the second connection, and information about
traffic to be transmitted and received through the second
connection.
In accordance with an embodiment of the present disclosure, the
method further includes identifying that the user equipment enters
coverage of the second connection using an indicator received
through the first connection prior to the detecting.
In order to solve the above problem, a user equipment supporting a
first radio access technology (RAT) and a second RAT in a mobile
communication system includes a transceiver unit configured to
transmit and receive signals and a controller configured to detect
whether a condition for activating a second connection based the
second RAT is satisfied through a first connection based the first
RAT and to release the second connection when the transmission and
reception of traffic through the second connection is completed and
a timer configured with respect to the second connection expires.
The timer for the second connection and a timer for the first
connection are differently configured.
In accordance with an embodiment of the present disclosure, the
condition for activating the second connection may be determined
based on the capacity of a buffer for data to be transmitted and
received by the user equipment, and the timer for the second
connection may be configured to be shorter than the timer for the
first connection.
In accordance with an embodiment of the present disclosure, the
controller may be configured to perform measurement on the second
connection prior to the detecting. The measurement may be performed
based on at least one of whether the user equipment is present in
coverage of the second connection, information about a service to
be provided through the second connection, and information about
traffic to be transmitted and received through the second
connection.
In accordance with an embodiment of the present disclosure, the
controller may be configured to identify that the user equipment
enters coverage of the second connection using an indicator
received through the first connection prior to the detecting.
In order to solve the above problem, a method of a base station to
communicate with a user equipment supporting a first radio access
technology (RAT) and a second RAT in a mobile communication system
includes activating a second connection with the user equipment
when the user equipment detects that a condition for activating the
second connection based the second RAT is satisfied through a first
connection based the first RAT and releasing the second connection
when the transmission and reception of traffic the second
connection is completed and a timer configured with respect to the
second connection expires. The timer for the second connection and
a timer for the first connection are differently configured.
In accordance with an embodiment of the present disclosure, the
condition for activating the second connection may be determined
based on the capacity of a buffer for data to be transmitted and
received by the user equipment. The timer for the second connection
may be configured to be shorter than the timer for the first
connection.
In accordance with an embodiment of the present disclosure, the
user equipment may perform measurement on the second connection
before the user equipment detects that the condition is satisfied.
The measurement may be performed based on at least one of whether
the user equipment is present in coverage of the second connection,
information about a service to be provided through the second
connection, and information about traffic to be transmitted and
received through the second connection.
In accordance with an embodiment of the present disclosure, before
the user equipment detects that the condition is satisfied, the
user equipment may identify that the user equipment enters coverage
of the second connection using an indicator received through the
first connection prior to the detecting.
In order to solve the above problem, a base station to communicate
with a user equipment supporting a first radio access technology
(RAT) and a second RAT in a mobile communication system includes a
transceiver unit configured to transmit and receive signals and a
controller configured to activate a second connection with the user
equipment when the user equipment detects that a condition for
activating the second connection based the second RAT is satisfied
through a first connection based the first RAT and to release the
second connection when the transmission and reception of traffic
the second connection is completed and a timer configured with
respect to the second connection expires. The timer for the second
connection and a timer for the first connection are differently
configured.
In accordance with an embodiment of the present disclosure, the
condition for activating the second connection may be determined
based on the capacity of a buffer for data to be transmitted and
received by the user equipment. The timer for the second connection
may be configured to be shorter than the timer for the first
connection.
In accordance with an embodiment of the present disclosure, the
user equipment may perform measurement on the second connection
before the user equipment detects that the condition is satisfied.
The measurement may be performed based on at least one of whether
the user equipment is present in coverage of the second connection,
information about a service to be provided through the second
connection, and information about traffic to be transmitted and
received through the second connection.
In accordance with an embodiment of the present disclosure, before
the user equipment detects that the condition is satisfied, the
user equipment may identify that the user equipment enters coverage
of the second connection using an indicator received through the
first connection prior to the detecting.
Advantageous Effects of Invention
Through the present disclosure, a power consumption reduction
effect of a UE is expected because the 5G cell RRC connected state
of UEs capable of a 5G multi-RAT is maintained to a minimum through
a CP tail minimization control operation of a BS. Furthermore, a
cost efficiency effect through a power consumption reduction in a
5G BS (RU/TRxP) is expected because a measurement operation for a
5G cell of a UE is limitedly performed. Furthermore, an increase in
radio resource use efficiency is expected through a reduction in 5G
inter-cell surrounding interference.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram schematically showing an Scell addition/release
operation method according to the dual connectivity of a
communication system.
FIG. 2 is a diagram showing an example of a small cell measurement
configuration and UE/BS operation according to the dual
connectivity of a communication system (e.g., 3GPP Release 12), and
is a diagram showing an operation for a UE to continuously perform
macrocell and small cell measurement and an operating process of a
UE and macrocell and small cell BSs in the RRC connected state.
FIG. 3 is a diagram showing an example of a core network
architecture and the connection state of a control plane (CP) and
user plane (UP) between a UE and a BS in an LTE-5G Tight
Integration (non-standalone (NSA)) operation environment according
to an embodiment of the present disclosure.
FIG. 4 is a diagram showing an example of a connection state
between BSs and signaling between protocol layers in an LTE-5G
Tight Integration (NSA) operation environment according to an
embodiment of the present disclosure.
FIG. 5 is an RRC connection management method for low energy of a
UE according to an embodiment of the present disclosure and is a
diagram illustrating a state diagram for a multi-RAT (4G, 5G) low
energy operation in an LTE-5G Tight Integration(NSA) operation
environment.
FIG. 6 is an RRC connection management method for low energy of a
UE according to an embodiment of the present disclosure and is a
diagram illustrating a UE modem operation process for each state
according to an operation scenario for a multi-RAT (4G, 5G) low
energy operation in an LTE-5G Tight Integration operation
environment.
FIG. 7 is an RRC connection management method for low energy of a
UE according to an embodiment of the present disclosure and is a
diagram illustrating a control signaling flow and a BS/UE modem
operation process for a multi-RAT (4G, 5G) low energy operation in
an LTE-5G Tight Integration operation environment.
FIG. 8 is a diagram showing an example of the connection state of a
control plane (CP) and user plane (UP) between a core network and a
BS in an LTE-5G Independent environment (multi-link (ML) or
standalone (SA)) according to an embodiment of the present
disclosure.
FIG. 9 is a diagram showing an example of a connection state
between BSs and signaling between protocol layers in an LTE-5G
Independent environment (multi-link (ML)) according to an
embodiment of the present disclosure.
FIG. 10 is a diagram illustrating a state diagram for a multi-RAT
(4G, 5G) low energy operation in an LTE-5G Independent operation
environment according to an embodiment of the present
disclosure.
FIG. 11 is a diagram illustrating a UE modem operation process for
each state according to an operation scenario for a multi-RAT (4G,
5G) low energy operation in an LTE-5G Independent operation
environment according to an embodiment of the present
disclosure.
FIG. 12 is a diagram illustrating a control signaling flow and a
BS/UE modem operation process for a multi-RAT (4G, 5G) low energy
operation in an LTE-5G Independent operation environment according
to an embodiment of the present disclosure.
FIG. 13 is a diagram showing an example in which a UE connection
standby time reduction operation is implemented based on a traffic
end point (TCP flag FIN) for an efficient 5G radio tail (user
inactivity timer) interval reduction operation according to an
embodiment of the present disclosure, and is a diagram illustrating
the final (FIN) indication of a TCP packet from a transmission
stage and reception stage and ACK transmission for identifying the
final (FIN) indication.
FIG. 14 is a diagram showing another example in which a UE
connection standby time reduction operation is implemented based on
a traffic end point (TCP flag FIN) for an efficient 5G radio tail
(user inactivity timer) interval reduction operation according to
an embodiment of the present disclosure, and is a diagram including
FIN indicative of the last of transmission as the type of flag
marked in a TCP header.
FIG. 15 is a diagram showing yet another example in which a UE
connection standby time reduction operation is implemented based on
a traffic end point (TCP flag FIN) for an efficient 5G radio tail
(user inactivity timer) interval reduction operation according to
an embodiment of the present disclosure, and is a diagram in which
a hierarchical structure and unit are marked in a wireless
communication protocol.
FIG. 16 is a diagram showing an example of an operation based on DL
traffic occurrence as a server operation according to a UE request
(UL) for a 5G CP Tail interval minimization control operation
according to an embodiment of the present disclosure.
FIG. 17 is a diagram showing an example of an operation based on DL
traffic occurrence as a server operation based on the cost of a
process for a UE to make transition from the RRC Idle state to the
RRC connected state for the purpose of a 5G CP Tail interval
minimization control operation according to an embodiment of the
present disclosure.
FIG. 18 is a diagram showing the configuration of a UE according to
an embodiment of the present disclosure.
FIG. 19 is a diagram showing the configuration of a BS according to
an embodiment of the present disclosure.
MODE FOR THE INVENTION
Hereinafter, various embodiments of the present disclosure are
described in detail with reference to the accompanying drawings. It
is to be noted that the same reference numerals are used throughout
the drawings to refer to the same elements. Furthermore, a detailed
description of the known functions or elements that may make the
gist of the present disclosure vague is omitted.
In this specification, in describing the embodiments, a description
of contents that are well known in the art to which the present
disclosure pertains and not directly related to the present
disclosure is omitted in order to make the gist of the present
disclosure clearer.
For the same reason, in the accompanying drawings, some elements
are enlarged, omitted, or depicted schematically. Furthermore, the
size of each element does not accurately reflect its real size. In
the drawings, the same or similar elements are assigned the same
reference numerals.
The merits and characteristics of the present disclosure and a
method for achieving the merits and characteristics will become
more apparent from the embodiments described in detail in
conjunction with the accompanying drawings. However, the present
disclosure is not limited to the disclosed embodiments, but may be
implemented in various different ways. The embodiments are provided
to only complete the disclosure of the present disclosure and to
allow those skilled in the art to understand the category of the
present disclosure. The present disclosure is defined by the
category of the claims. The same reference numerals will be used to
refer to the same or similar elements throughout the drawings.
In the present disclosure, it will be understood that each block of
the flowchart illustrations and combinations of the blocks in the
flowchart illustrations can be executed by computer program
instructions. These computer program instructions may be mounted on
the processor of a general purpose computer, a special purpose
computer, or other programmable data processing apparatus, so that
the instructions executed by the processor of the computer or other
programmable data processing apparatus create means for executing
the functions specified in the flowchart block(s). These computer
program instructions may also be stored in computer-usable or
computer-readable memory that can direct a computer or other
programmable data processing equipment to function in a particular
manner, such that the instructions stored in the computer-usable or
computer-readable memory produce an article of manufacture
including instruction means that implement the function specified
in the flowchart block(s). The computer program instructions may
also be loaded into a computer or other programmable data
processing apparatus to cause a series of operational steps to be
performed on the computer or other programmable apparatus to
produce a computer-executed process, so that the instructions
performing the computer or other programmable apparatus provide
steps for executing the functions described in the flowchart
block(s).
Furthermore, each block of the flowchart illustrations may
represent a portion of a module, a segment, or code, which includes
one or more executable instructions for implementing a specified
logical function(s). It should also be noted that in some
alternative implementations, the functions noted in the blocks may
occur out of order. For example, two blocks shown in succession may
in fact be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved.
The term "unit", as used in the present embodiment means software
or a hardware component, such as a field programmable gate array
(FPGA) or an application-specific integrated circuit (ASIC), and
the "unit" performs specific tasks. The "unit" may advantageously
be configured to reside on an addressable storage medium and
configured to operate on one or more processors. Accordingly, the
"unit" may include, for example, components, such as software
components, object-oriented software components, class components,
and task components, processes, functions, attributes, procedures,
sub-routines, segments of program code, drivers, firmware,
microcode, circuitry, data, databases, data structures, tables,
arrays, and variables. The functionalities provided in the
components and "units" may be combined into fewer components and
"units" or may be further separated into additional components and
"units." Furthermore, the components and "units" may be implemented
to operation on one or more CPUs within a device or a security
multimedia card.
The present disclosure proposes an operation of a base station (BS)
and user equipment (UE) and an apparatus therefor, for achieving
energy efficiency KPI being discussed in a 3.sup.rd generation
partnership project (3GPP) radio access network (RAN) 5 generation
(5G) communication system standardization process. In the
corresponding standard, an energy efficient operation is defined by
aiming at a main target of improving power efficiency [bit/J] of a
UE and BS network 1000 times or more within 10 years. To this end,
in an mmWave operation of a high frequency band, a control method
of reducing the active operation time of a UE is being discussed in
order to solve an additional power consumption possibility
according to an essential beamforming transmission method.
The present disclosure proposes contents regarding a method of
controlling and maintaining an RRC connection in an LTE-5G Tight
Integration environment (non-stand alone environment (NSA)) and an
LTE-5G Independent environment (stand alone environment (SA)) based
on multi-link (ML), that is, 5G network architecture candidates. In
particular, there is proposed a control process of minimizing a CP
tail (radio tail or user inactivity timer), that is, the remaining
maintenance time of the RRC connected state of a BS, if beamforming
transmission in an mmWave band, that is, a high frequency band, is
performed. Accordingly, there is proposed a method of supporting
the function of maintaining a 5G cell RRC connected state to a
minimum in order to minimize battery power consumption of a network
and UEs operating through a multi-RAT modem (LTE and 5G).
In a wireless communication UE, the RRC state for transmitting and
receiving data has been conservatively designed based on the design
of a previous generation based on a voice call. For example, a UE
has severe power consumption because it maintains a standby time
(e.g., Connected DRX) in the RRC connected state although there is
no traffic arrival for a given time after traffic reception.
Furthermore, in the case of a smartphone user, data, such as a keep
alive message not related to user quality of service (QoS),
frequently occurs. If an RRC connection therefor is maintained as
at the present, user equipment power consumption may become further
deteriorated.
Through the present disclosure, a power consumption reduction
effect of a UE is expected because the 5G cell RRC connected state
of 5G multi-RAT UEs is maintained to a minimum through CP tail
minimization control of a BE. Furthermore, there is proposed a
method of improving cost efficiency through a reduction in the
power consumption of a 5G BS (RU/TRxP) and radio resource use
efficiency through a reduction in 5G inter-cell surrounding
interference because a 5G cell measurement operation of a UE is
limitedly performed.
In the following description of description of the present
disclosure, a radio access technology (RAT) named 5G is a new RAT
for supporting high capacity traffic, and refers to an RAT that
belongs to RATs supported by a multi-RAT capable UE and that is
capable of higher QoS support, such as a high link capacity or
shorter latency. In contrast, a legacy RAT refers to an RAT that
belongs to RATs supported by a multi-RAT capable UE and that is
capable of relatively low QoS support, but is advantageous in the
energy efficiency aspect because power consumption is small.
Furthermore, the 5G RAT may be understood as a high frequency BS
due to the nature of an occupied frequency band. In this case, 4G
LTE, that is, the legacy RAT, may be understood as a low frequency
BS because it occupies a relatively low frequency band. Meanwhile,
a sub-6 GHz band and an above-6 GHz band are functionally separated
within a communication system according to the 5G RAT, and may be
responsible for the roles of the aforementioned low frequency BS
and high frequency BS.
In accordance with another embodiment, the following contents of
the invention may also be applied to a communication system in
which a 4G cell operates as a master node (MN) and an NR mmWave
cell operates as a secondary node (SN) and may also be applied to a
communication system in which a sub-6 GHz (low frequency (LF)) BS
operates as a master node (MN) and an above-6 GHz (high frequency
(HF)) BS operates as a secondary node (SN).
First, FIG. 1 is a diagram schematically showing an Scell
addition/release operation method according to the dual
connectivity of a communication system. In accordance with a dual
connectivity (e.g., described in 3GPP Release 12 small cell
enhancement) operation, a macrocell BS controls the RRC connection
of a small cell through an RRC message and adds/releases the
connection with the small cell. The Scell link connection of a UE
is controlled based on such control. A paging operation providing
notification of whether data has been reached in the RRC idle state
of a UE also operates through a macrocell link.
FIG. 2 is a diagram showing an example of a small cell measurement
configuration and UE/BS operation according to the dual
connectivity of a communication system (e.g., 3GPP Release 12). In
FIG. 2, the UE continuously performs measurement on a macrocell and
a small cell and operates along with macrocell and small cell BSs
in the RRC connected state.
When a small cell measurement configuration for dual connectivity
(e.g., described in 3GPP Release 12) is completed through an RRC
reconfiguration message (S210), the UE/BS perform (S270)
measurement on the small cell and a measurement report (MR) process
(S220, S230). Next, the UE operates (in RRC_Connected) (S280) by
turning on an Scell modem based on an addition message (RRC
Message, S240) for the small cell from the macrocell BS. In
particular, the UE continues to perform measurement on the Scell
even prior to the Scell addition. The UE turns off the Scell modem
based on a release message (RRC message, S260) for the small cell
from the macrocell BS. Such a dual connectivity technology has a
problem in that power consumption of a UE is deteriorated because
the UE must continuously perform measurement on a macrocell and a
small cell and the UE turns on a plurality of modems (performs
macrocell and small cell operations) in the RRC connected
state.
When power consumption in an mmWave beamforming environment of a
high frequency band is taken into consideration, an inefficiency
problem in the power consumption aspect becomes further great if
the same/similar frequency band environment in the aforementioned
dual connectivity operation (a macrocell and small cell link
operation in the sub 6 GHz band) is applied to 5G without any
change.
Accordingly, the present disclosure solves the above problem and
also needs to satisfy the following contents. First, in the present
disclosure, an Idle interval needs to be expanded and UE power
efficiency needs to be improved by minimizing a 5G cell RRC
connected state through CP tail minimization control of a BS.
Furthermore, a 5G cell link activation state (RRC connected state
and a measurement operation) of a UE is minimized and user QoS also
needs to be satisfied (latency criterion is satisfied).
Furthermore, network (N/W) signaling overhead and power consumption
of a UE, occurring due to frequent transition from the Idle state
to the connected state although a UE enters an early Idle state due
to a CP tail reduction, need to be minimized.
FIG. 3 is a diagram showing an example of a core network
architecture and the connection state of a control plane (CP) and
user plane (UP) between a UE and a BS in an LTE-5G Tight
Integration (non-standalone (NSA)) operation environment according
to an embodiment of the present disclosure. In one embodiment, a
process of selectively operating a measurement operation for a 5G
cell of a UE is described as a first operation method for
minimizing the 5G link activation state of a UE.
When the 5G cell modem of a UE operates in a high frequency band,
power consumption is caused in a process of transmitting and
receiving common control signals (e.g., synchronization, system
information, and a reference signal) through beamforming
transmission. In contrast, a multi-RAT capable UE may transmit and
receive traffic of a low data rate through a legacy RAT (4G/3G/2G,
etc.) prior to 5G, and is thus advantageous from the viewpoint of
power consumption in minimizing the activation state of a 5G cell
link within the UE for the traffic transmission of a higher data
rate. A UE chiefly operates in the standby time not having
transmission rather than a transmission progress time for a 5G cell
link. Accordingly, such an improved measurement operation is very
important for the power efficiency improvement of a UE.
An RRC state operation between the LTE and 5G connections of a
multi-RAT capable UE may chiefly operate according to the following
two methods. The first is an LTE-5G interworking operation shown in
FIGS. 3 to 7, and is a BS and UE operation in a 5G non-standalone
(NSA) environment. The second is an LTE-5G independent operation
shown in FIGS. 8 to 12 and is a BS and UE operation in a 5G
standalone (SA) environment.
FIG. 3 is a diagram showing an example of a core network
architecture and a control plane (CP) and user plane (UP)
connection state between a UE and a BS in an LTE-5G Tight
Integration (NSA) operation environment, that is, one of 5G network
architecture candidates, in a communication system according to an
embodiment of the present disclosure. In the NSA environment shown
in FIG. 3, an LTE BS can operate as a macrocell and provide wider
coverage because it uses a frequency band of 6 GHz or less. A 5G BS
can operate as a small cell because it uses frequency bands of 28
GHz and 6 GHz or more including an mmWave band. In this case, the
4G and 5G core networks are separately present, but there is an
interface connecting them. A 4G (LTE) link can connect both a
control plane (CP) and user plane (UP) between a UE and a BS. In
contrast, 5G (new radio (NR)) can connect both a control plane (CP)
and user plane (UP) between a UE and a BS or may assume an
operation in which a control plane (CP) between a UE and a BS fully
depend on an LTE BS or only a user plane (UP) is performed based on
a 5G connection. As another operation example, an operation of
implementing some control functions of a control plane (CP) between
a UE and a BS in an LTE BS, implementing the remaining control
functions through a 5G link, and transmitting and receiving a user
plane (UP) through a 5G connection may be considered.
FIG. 4 is a diagram showing an example of a connection state
between BSs and signaling between protocol layers in an LTE-5G
Tight Integration (NSA) operation environment, that is, one of 5G
network configuration candidates according to an embodiment of the
present disclosure. FIG. 4 divides and shows whether 4G and 5G
protocol layers will operate a radio resource control (RRC) layer,
a packet data convergence protocol (PDCP) layer, a radio link
control (RLC) layer, a medium access control (MAC) layer and a
physical (PHY) layer as independent protocol layers or a merged
protocol layer. In 5G, a so-called "option 2" structure in which
the PDCP layer and the RLC layer are basically separated and
implemented is discussed. For example, there is a method for the 4G
and 5G protocol layers to operate the RLC, MAC and PHY layers as
independent protocol layers and to merge and operate the RRC layer
and the PDCP layer.
FIG. 5 is an RRC connection management method for low energy of a
UE and is a diagram illustrating a state diagram for a multi-RAT
(4G, 5G) low energy operation in the LTE-5G Tight Integration(NSA)
operation environment.
In the embodiment shown in FIG. 5, detailed operation scenarios of
a UE include 1) a 5G link activation necessity and availability
sensing operation, 2) a 5G modem turn-on time determination
operation, and 3) a different configurations and application
operations of C-DRX standby intervals of 4G and 5G in the RRC
connected state.
First, 1) a UE needs to perform a preliminary operation (e.g., beam
scanning or measurement) before it turns on a high frequency band
modem receiver of 5G (NW). In accordance with one embodiment, at
least one of a) whether a UE is in coverage of a NR BS, b) QoS
necessary for service information (e.g., service type) and service
of traffic that needs to be transmitted, and c) the amount of data
for traffic that requires transmission support and the state of a
buffer accumulated in a UE/BS (i.e., the amount of data accumulated
in a buffer) may be selected as a criterion for detecting that such
a preliminary operation needs to be started.
In the above embodiment, a process of performing the aforementioned
preliminary operation (beam scanning and/or measurement) may be
configured by a 4G BS not a 5G BS, and may be performed by a UE.
More specifically, a 4G BS may configure a condition for triggering
an event for a preliminary operation performed by a UE. The UE
performs the preliminary operation (beam scanning and/or
measurement) on a 5G BS in response to the event configured by the
4G BS.
In the LTE-5G Tight Integration (NSA) environment, a 5G RAT
connection may be supported through a 4G RAT connection between a
UE and an LTE BS. When a UE is first connected to a network, a 4G
modem is first turned on (510). Next, the UE moves and enters 5G
Coverage. When such an operation of the UE is sensed, the UE
performs a 5G discovery operation (520). In this case, a process of
sensing the entry into 5G coverage includes a determination
operation based on indication provided by a BS (network). For
example, a 5G indicator of 1 bit may be newly added on system
information broadcasted by a 4G BS. Accordingly, the UE that has
received a 5G indicator from a 4G BS may be aware that a 5G BS is
present within coverage of the corresponding 4G BS. The UE starts
scanning in a 5G (NR)-related frequency band. At this time, 5G
coverage-related indication provided by the BS (network) will be
transmitted as system information of an LTE BS because the UE has
not yet turned on the high frequency band modem receiver of 5G
(NW). In this case, the 5G indicator of 1 bit is information for
notifying the UE that a 5G small cell is present within a macrocell
of the corresponding LTE BS.
Next, a service type of uplink or downlink traffic (e.g., when a
high-capacity data service of an enhanced mobile broadband (eMBB)
starts, when a ultra-reliable low latency communication (URLLC)
service of low latency starts, etc) may become another criterion as
the criterion for an operation for a UE to start 5G scanning in
addition to the indication provided by a BS (network). When
uplink/downlink traffic of the aforementioned given service occurs,
a UE may start a preliminary operation (scanning or measurement)
for turning on the high frequency band modem receiver of 5G (NW).
Furthermore, the UE may start a preliminary operation (scanning or
measurement) for turning on the high frequency band modem receiver
of 5G (NW) using the amount of uplink or downlink traffic, expected
by the UE or the BS, as another criterion.
Unlike in the 5G indicator of 1 bit, if it is determined that a
preliminary operation needs to be started based on the service type
and amount of downlink traffic, there is a need for indication
provided by a BS (network) through which the BS notifies a UE of
the service type and amount. In accordance with one embodiment, a
BS may transmit an RRC (re)configuration message to a UE using a
unicast method. In accordance with another embodiment, a method for
a network to instruct a UE to perform the preliminary operation by
transmitting on-demand system information is also possible as an
operation for a BS to notify the UE that the UE needs to start a
preliminary operation (scanning or measurement) for turning on the
modem receiver of an NR (5G) frequency band.
Furthermore, if it is determined that a preliminary operation needs
to be started based on the service type and amount of uplink
traffic, a UE transmits a traffic event report to a BS through a 4G
RAT or a low frequency link as UE feedback by notifying the BS of
the need of the preliminary operation. In accordance with one
embodiment, a BS may transmit an RRC (re)configuration message to a
UE using a unicast method based on the traffic event report of the
UE. In accordance with another embodiment, a method for a network
to instruct a UE to perform a preliminary operation by transmitting
system information, common system information (or minimum system
information), on-demand system information or other system
information is also possible as an operation for a BS to notify a
UE that a preliminary operation (e.g., beam scanning and/or
measurement) for turning on the modem receiver of an NR (5G)
frequency band needs to be started.
When a UE recognizes that it needs to start a preliminary operation
(scanning or measurement) for turning on the high frequency band
modem receiver of 5G (NW) through an indicator transmitted by a 4G
BS according to the aforementioned process or through an RRC
(re)configuration or on-demand SI provided by a BS (network), the
UE may identify that it will start the preliminary operation for
turning on the 5G modem by transmitting a response signal to the
BS.
Next, an operation for a UE to determine a 5G modem turn-on time
(5G ON time determination) after a 5G discovery process is
terminated may operate based on a) a buffer state for each UE of a
BS and b) the buffer state of a UE. Various layers, such as i) the
PDCP layer, ii) the RLC layer, iii) the MAC layer, and iv) the PHY
layer, may correspond to protocol layers, that is, a criterion for
the buffer state of a BS and a UE. For example, if the 5G modem
turn-on time is determined based on the PDCP buffer, the 5G modem
of the UE will be turned on based on the PDCP buffer state of each
UE of a BS and/or the PDCP buffer state of a UE (530).
More specifically, when the capacity of a buffer for each UE of a
BS or the capacity of the buffer of the UE increases to a threshold
TH_1 or more, first, the BS recognizes that it needs to start a
preliminary operation (scanning or measurement) for turning on the
high frequency band modem receiver of 5G (NW) (520). Thereafter,
when the capacity of a buffer for each UE of a BS or the capacity
of the buffer of the UE increases to a second threshold TH_2
(TH_1<TH_2) or more, an operation of turning on the 5G (NR) high
frequency band modem receiver of the UE is performed (530).
Meanwhile, the aforementioned two operations (preliminary operation
and 5G modem turn-on operation prior to 5G modem turn-on) according
to the capacity of a buffer may be started based a 5G link
activation request signal of a UE or BS, may be performed based on
the time when the reception of a response feedback message
corresponding to such an activation request signal is completed or
may be performed by starting data transmission after a timer (time
gap for configuring a transmission and reception (Tx/Rx) beam of a
UE and a BS) configured in the aforementioned response feedback
message.
In accordance with another embodiment, the operation for the UE to
determine the 5G modem turn-on time (5G ON time determination)
after the 5G discovery process is terminated may be determined
based on c) PDCP duplication activation. More specifically, the
operation includes an operation for a master node (4G macrocell, a
lower frequency BS) to configure whether to activate PDCP
duplication in RRC based on a PDCP duplication operation and to
determine the 5G modem turn-on time based on an operation of
dynamically controlling whether to activate PDCP duplication
through a MAC CE.
Furthermore, the operation for the UE to determine the 5G modem
turn-on time (5G ON time determination) after the 5G discovery
process is terminated may be determined based on d) mobility
support according to UE mobility speed (performance requirements
for a handover failure, handover latency and a radio link failure).
In accordance with one embodiment, when UE moving speed is high
speed and thus a threshold (e.g., 120 km/h) or more and a handover
latency requirement is a threshold (e.g., 1 second or 0) or less,
the operation is performed using an MN link, and includes an
operation of performing data transmission without turning on an SN
or using a continuously turned-on SN without turning off the SN.
Furthermore, the operation includes an operation of performing
mobility support of a UE through a continuously turned-on MN
without turning off the MN.
Next, the different configurations and application operations of
C-DRX standby intervals of 4G and 5G in the RRC connected state,
from among the aforementioned embodiments, is described. An
operation for the 4G/5G CP Tail differentiation operations
according to one embodiment may include an operation of first
changing a 5G Link to a low energy mode (C-DRX or Idle DRX) if
there is no transmitted and received traffic. For example, when the
user-inactivity timer (i.e., CP tail) of a 5G modem is determined
and set to 1 second and the user-inactivity timer of a 4G modem is
determined and set to 10 seconds, the 5G modem may be first
deactivated after 1 second from the last transmission and reception
traffic, and the 4G modem may remain in the C-DRX state and may be
deactivated after 10 seconds, so the UE makes transition to the RRC
idle state.
Meanwhile, low energy operation-related parameters in the RRC
layer-related standard document 3GPP TS 36.331 are described like
Table 1 to Table 4.
TABLE-US-00001 TABLE 1 MAC-MainConfig field descriptions drx-Config
Used to configure DRX as specified in TS 36.321 [6]. E-UTRAN
configures the values in DRX-Config-v1130 only if the UE indicates
support for IDC indication. E-UTRAN configures drx-Config-v1130
only if drx-Config (without suffix) is configured.
drx-InactivityTimer Timer for DRX in TS 36.321 [6]. Value in number
of PDCCH sub-frames. Value psf1 corresponds to 1 PDCCH sub-frame,
psf2 corresponds to 2 PDCCH sub-frames and so on.
drx-RetransmissionTimer Timer for DRX in TS 36.321 [6]. Value in
number of PDCCH sub-frames. Value psf1 corresponds to 1 PDCCH
sub-frame, psf2 corresponds to 2 PDCCH sub-frames and so on. In
case drx-RetransmissionTimer-v1130 is signalled, the UE shall
ignore drx-RetransmissionTimer (i.e. without suffix).
drxShortCycleTimer Timer for DRX in TS 36.321 [6]. Value in
multiples of shortDRX-Cycle. A value of 1 corresponds to
shortDRX-Cycle, a value of 2 corresponds to 2 * shortDRX-Cycle and
so on.
TABLE-US-00002 TABLE 2 DRX-Config ::= CHOICE { release NULL, setup
SEQUENCE { onDurationTimer ENUMERATED { psf1, psf2, psf3, psf4,
psf5, psf6, psf8, psf10, psf20, psf30, psf40, psf50, psf60, psf80,
psf100, psf200}, drx-InactivityTimer ENUMERATED { psf1, psf2, psf3,
psf4, psf5, psf6, psf8, psf10, psf20, psf30, psf40, psf50, psf60,
psf80, psf100, psf200, psf300, psf500, psf750, psf1280, psf1920,
psf2560, psf0-v1020, spare9, spare8, spare7, spare6, spare5,
spare4, spare3, spare2, spare1}, drx-RetransmissionTimer ENUMERATED
{ psf1, psf2, psf4, psf6, psf8, psf16, psf24, psf33},
longDRX-CycleStartOffset CHOICE { sf10 INTEGER(0..9), sf20
INTEGER(0..19), sf32 INTEGER(0..31), sf40 INTEGER(0..39), sf64
INTEGER(0..63), sf80 INTEGER(0..79), sf128 INTEGER(0..127), sf160
INTEGER(0..159), sf256 INTEGER(0..255), sf320 INTEGER(0..319),
sf512 INTEGER(0..511), sf640 INTEGER(0..639), sf1024
INTEGER(0..1023), sf1280 INTEGER(0..1279), sf2048 INTEGER(0..2047),
sf2560 INTEGER(0..2559) }, shortDRX SEQUENCE { shortDRX-Cycle
ENUMERATED { sf2, sf5, sf8, sf10, sf16, sf20, sf32, sf40, sf64,
sf80, sf128, sf160, sf256, sf320, sf512, sf640}, drxShortCycleTimer
INTEGER (1..16) } OPTIONAL -- Need OR } } DRX-Config-v1130 ::=
SEQUENCE { drx-RetransmissionTimer-v1130 ENUMERATED {psf0-v1130}
OPTIONAL, --Need OR longDRX-CycleStartOffset-v1130 CHOICE {
sf60-v1130 INTEGER(0..59), sf70-v1130 INTEGER(0..69) } OPTIONAL,
--Need OR, shortDRX-Cycle-v1130 ENUMERATED {sf4-v1130} OPTIONAL
--Need OR }
TABLE-US-00003 TABLE 3 RRM-Config field descriptions
ue-InactiveTime Duration while UE has not received or transmitted
any user data. Thus the timer is still running in case e.g., UE
measures the neighbour cells for the HO purpose. Value s1
corresponds to 1 second, s2 corresponds to 2 seconds and so on.
Value min1 corresponds to 1 minute, value min 1s20 corresponds to 1
minute and 20 seconds, value min1s40 corresponds to 1 minute and 40
seconds and so on. Value hr1 corresponds to 1 hour, hr1min30
corresponds to 1 hour and 30 minutes and so on.
TABLE-US-00004 TABLE 4 -- ASN1START RRM-Config ::= SEQUENCE {
ue-InactiveTime ENUMERATED { s1, s2, s3, s5, s7, s10, s15, s20,
s25, s30, s40, s50, min1, min1s20c, min1s40, min2, min2s20, min3,
min3s30, min4, min5, min6, min7, min8, min9, min10, min12, min14,
min17, min20, min24, min28, min33, min38, min44, min50, hr1,
hr1min30, hr2, hr2min30, hr3, hr3min30, hr4, hr5, hr6, hr8, hr10,
hr13, hr16, hr20, day1, day1hr12, day2, day2hr12, day3, day4, day5,
day7, day10, day14, day19, day24, day30, dayMoreThan30} OPTIONAL,
....
For the different configurations and application operations of
C-DRX standby intervals of 4G and 5G, in accordance with one
embodiment, drx-Config, drx-InactivityTimer,
drx-RetransmissionTimer, and drxShortCycleTimer parameters included
in the MAC-MainConfig field configured between a UE and a BS, the
ue-InactiveTime parameter of the RRM-Config field, and a setting
value corresponding to a sub-parameter, described in Table 1 to
Table 4, may be separated, configured and applied as an LTE set (or
low/lower frequency or a sub-6 GHz link) and an NR set (or
high/higher frequency or an above-6 GHz link) not one set in
5G.
For example, as in Table 5 and Table 6 below, a UE can
differentially configure and operate C-DRX standby intervals of 4G
and 5G by configuring separate drx sets for 5G in the
MAC-MainConfig field and the RRM-Config field. In Table 5 and Table
6, "nr" is added to a parameter configuring a new drx set for 5G
and indicated. In this case, the parameters shown in Table 5 and
Table 6 are merely simple examples, and other parameters may be
additionally configured in order to differently operate C-DRX
between 4G and 5G. Conversely, in the described embodiment,
parameters may be configured in a form in which some parameters
have been omitted. As one method for differently operating C-DRX
between 4G and 5G, the parameters to which "nr" has been added for
a 5G connection may be configured as a value shorter than or longer
than parameters for a 4G connection, and some parameters may be
configured as the same value.
TABLE-US-00005 TABLE 5 DRX-Config ::= CHOICE { release NULL, setup
SEQUENCE { onDurationTimer ENUMERATED { }, drx-InactivityTimer
ENUMERATED { }, drx-RetransmissionTimer ENUMERATED { },
longDRX-CycleStartOffset CHOICE { }, shortDRX SEQUENCE {
shortDRX-Cycle ENUMERATED{ }, drxShortCycleTimer INTEGER (1..16) }
OPTIONAL -- Need OR } } DRX-Config-v1130 ::= SEQUENCE {
drx-RetransmissionTimer-v1130 ENUMERATED {psf0-v1130} OPTIONAL,
--Need OR longDRX-CycleStartOffset-v1130 CHOICE { sf60-v1130
INTEGER(0..59), sf70-v1130 INTEGER(0..69) } OPTIONAL, --Need OR
shortDRX-Cycle-v1130 ENUMERATED {sf4-v1130} OPTIONAL, --Need OR }
DRX-Config-nr ::= SEQUENCE { onDurationTimer_nr ENUMERATED { },
drx-InactivityTimer_nr ENUMERATED { }, drx-RetransmissionTimer_nr
ENUMERATED { }, longDRX-CycleStartOffset_nr CHOICE { }, shortDRX_nr
SEQUENCE { shortDRX-Cycle_nr ENUMERATED{ }, drxShortCycleTimer_nr
INTEGER (1..16) }
TABLE-US-00006 TABLE 6 -- ASN1START RRM-Config ::= SEQUENCE {
uc-InactiveTime ENUMERATED { } OPTIONAL, .... RRM-Config_nr ::=
SEQUENCE { uc-InactiveTime_nr ENUMERATED { } OPTIONAL, ....
According to the aforementioned embodiment, in a process of
dualizing C-DRX parameters for a 4G connection and a 5G connection,
several criteria may be applied. First, if the parameters are
classified based on a communication generation, they are classified
based on a 4G connection and a 5G connection. Second, the
parameters may be classified for each frequency band. For example,
parameters related to a 6 GHz or less frequency band link and a 6
GHz or more frequency band link may be dualized and configured.
Third, a method of dualizing and configuring the parameters
depending on beamforming is possible. Fourth, a method of dualizing
and configuring the parameters based on a beam number threshold
(wide beam and narrow beam) is possible. Finally, a method of
dualizing and configuring the parameters based on a modem having
high power efficiency and a modem having low power efficiency is
possible. In a process of dualizing and configuring the
C-DRX-related parameters according to the aforementioned several
criteria, an embodiment in which two or more criteria are complexly
applied is possible.
The parameters dualized and configured according to the
aforementioned embodiment may include the drx-Config,
drx-InactivityTimer, drx-RetransmissionTimer, and
drxShortCycleTimer parameter corresponding to the MAC-MainConfig
field related to the illustrated Connected DRX (C-DRX), and
ue-InactiveTime of the RRM-Config field. In addition, the
parameters may further include other parameters and some of the
parameters may be excluded.
In accordance with the aforementioned embodiment and another
embodiment, a user-inactivity timer, that is, a timer for the RRC
state transition of a UE, may be differentially configured and
operated for each 4G/5G link. The user-inactivity timer is a
parameter related to the aforementioned CP tail and radio tail.
When the user-inactivity timer expires, a UE releases an RRC
connection and operates in the RRC idle state. In this case, for
example, if a BS implements and applies User-inactivity timer_1 and
User-inactivity timer_2 as separate parameters or configures them
in the UE, when a corresponding timer expires, the UE can
automatically release an RRC connection and make transition to an
idle state or inactive state even without signaling to the BS.
That is, the aforementioned process may be separately applied to a
timer, that is, a criterion for switching from the RRC connected
state to the idle state, and a timer, that is, a criterion for
switching from the RRC connected state to the inactive state. This
may mean an operation of changing the RRC state from Connected to
the idle or inactive state through RRC signaling (RRC release or
RRC inactivation signaling) when a corresponding timer expires.
Meanwhile, in the present embodiment, the user-inactivity timer a)
may be dualized and configured with respect to a 4G link and a 5G
link, b) may be configured by dualizing related parameters with
respect to a 6 GHz or less frequency band link and a 6 GHz or more
frequency band link for each frequency band, c) may be configured
by dualizing related parameters depending on beamforming, d) may be
configured by dualizing related parameters based on a beam number
threshold (wide beam and narrow beam), and e) may be configured by
dualizing related parameters based on a modem having high power
efficiency and a modem having low power efficiency. The parameters
may be dualized and configured through a combination of two or more
of the aforementioned criteria.
In the aforementioned embodiment, in an embodiment in which DRX and
inactivity timer sets of an HF and a LF are differentiated,
configured and operated, a method for a BS to set corresponding
parameters as fixed values and operating them is possible.
In accordance with another embodiment, parameters related to DRX
and an inactivity timer may also be determined and configured based
on whether each of requirements for whether coverage of a secondary
node (SN) BS is included, service information of traffic and QoS
required by a service, the amount of data for traffic, the state
(amount) of a buffer accumulated in a UE/BS, whether PDCP
duplication is activated, mobility speed of a UE, and mobility
support, and a combination of two or more of them. That is, an
event trigger, defined based on each of conditions based on the
cases where a UE is in coverage of a secondary node (SN) BS,
service information of traffic and QoS required by a service are
low latency or a high capacity, the amount of data for traffic and
a buffer capacity accumulated in a UE/MN or an SN BS is a threshold
or more, and a PDCP Duplication operation is activated and thus a
PDCP packet is transmitted and received both links of the MN and
SN, and in the case of mobility support (handover and radio link
failure performance requirements) according to UE mobility speed
and defined based on a combination of a plurality of the
conditions, may be configured and applied.
Furthermore, an embodiment in which the values of a C-DRX parameter
and user inactivity timer for an SN link are conservatively
determined and set based on the aforementioned contents may also be
taken into consideration. An embodiment in which the values of a
C-DRX parameter and user inactivity timer for an MN link are
conservatively determined and set may also be taken into
consideration. In this case, the meaning that the values are
conservatively determined and set may mean a method of setting the
user inactivity timer relatively long, a method of setting
drx-Config and drx-InactivityTimer, that is, sub-parameters of
C-DRX, relatively long, a method of setting drx-RetransmissionTimer
relatively long, or a method of setting drxShortCycleTimer
relatively long.
In accordance with the aforementioned embodiment, in FIG. 5, when
traffic does not occur in the state 530, the UE enters a C-DRX mode
based on the 5G C-DRX parameter (540). Next, the UE first enters a
5G discovery state when the CP tail of a relatively shorter
configured 5G connection expires based on the dualized and
configured user-inactivity timer (550). That is, the CP tail
operates relatively shorter with respect to a 5G connection,
thereby being capable of reducing power consumption of the UE for
the 5G connection. Next, when the user-inactivity timer configured
with respect to the 4G connection of the UE expires and the RRC
connection is released, the UE operates in the RRC idle state
(560). In this case, although a plurality of modems supporting
different RATs is driven, the UE has one RRC state at one time.
Accordingly, the UE becomes the RRC connection state other than the
RRC idle state (560), that is, the state in which all the modems
for the 4G connection and the 5G connection have been turned
off.
As another embodiment for implementing 1) the 5G link activation
necessity and availability sensing operation (510, 520), 2) the 5G
modem turn-on time determination operation (520, 530), and 3) the
different configurations and application operations of C-DRX
standby intervals of 4G and 5G in the RRC connected state (570)
using the aforementioned detailed operation scenarios, a method of
i) introducing a an extended long-period discovery reference signal
(RS) design for a low energy operation of a UE and ii) operating 4G
LTE link C-DRX or Idle DRX when a 5G (NR) link is activated is also
possible. In this case, in a method of configuring an LTE DRX
period depending on moving speed and latency requirements of a UE,
a method of operating C-DRX or Idle DRX may also be implemented if
the UE is a low-speed moving state and the latency requirement is
not low latency and permits some latency.
FIG. 6 is an RRC connection management method for low energy of a
UE and is an embodiment of a UE modem operation for each state
according to operation scenarios for a multi-RAT (4G, 5G) low
energy operation in the LTE-5G Tight Integration operation
environment. FIG. 6 shows that operations of the 4G modem and 5G
modem of a UE are separated depending on the number of cases and
the operation scenarios of the UE according to the cases are
matched.
A more detailed operation of the UE is described below. The
operation of the UE may be divided into four modes depending on
whether a multi-RAT modem (4G, 5G) is activated.
(mode 1) a mode in which the 5G cell modem operation of a UE is
turned off, a UE operation mode in which a control signal and data
are received through a 4G LTE link;
(mode 2) a UE operation mode in which the 5G cell modem of a UE is
partially turned on in an extended long-period (TP1) and whether
the UE is in 5G cell coverage is identified (discovery operation)
based on whether a 5G cell received signal is a threshold or
more;
(mode 3) a mode in which the 5G cell modem of a UE is turned on in
a middle period (TP2) and the UE measures average channel quality
for each 5G cell (RU/TRP/ID) and transmits feedback for handover
and cell selection
(mode 4) a UE operation mode in which the 5G cell modem of a UE is
turned on in a short period (TP3) and the UE measures 5G cell
channel quality and the best beam and feeds them back and feeds
information for transmission and reception dedicatedly
(RU/TRxP/Cell ID) back.
In this case, the modem operation period of the UE is assumed to be
(TP1>TP2>TP3>0).
Separately from the four operation modes of the UE, in the
discovery process of the UE, the following operation mode change
condition (triggering event) may be configured with respect to
measurement operation options.
First, an event according to the relation between the movement of a
UE and 5G coverage may be configured. For example, the event
according to the relation between the movement of a UE and cell
coverage may include (1-1) a triggering event in which the UE moves
into 5G coverage, (1-2) a triggering event in which the UE moves
out of 5G coverage, and (1-3) a triggering event in which the UE
moves to a 5G coverage cell center. In the present embodiment, a
determination of whether the UE is in 5G coverage may include i) a
determination operation based on network (N/W) information (e.g.,
ANDSF, MME Pre-configuration information) and a message structure
of Pre-configuration information and ii) an operation based on an
Indication Message of a Legacy RAT BS a Tight-Interworking or
multi-link operation within a multi-RAT UE. For example, this
includes the design of a new message structure (new field), such as
a 1 bit 5G cell indicator within an RRC connection response
message, an operation for a BS to configure the new field, signal
it to a UE, and apply it to the UE. Furthermore, a determination of
whether the UE is in 5G coverage includes iii) an operation based
on a signal received from a legacy RAT BS in a Tight-Interworking
or multi-link within a multi-RAT UE. Whether the UE is in 5G
coverage may be determined by combining the aforementioned three
criteria i), ii) and iii).
Second, an event operation may be configured based on a buffer size
within a UE. All of PDCP/RLC/MAC/PHY buffers within a UE may
correspond to such a buffer. Furthermore, all of PDCP/RLC/MAC/PHY
buffers for each UE, supported by BSs of a legacy RAT and new RAT,
may correspond to such a buffer. An event according to the buffer
sizes of a UE and a BS is divided into the number of cases and
described in detail.
(2-1) Event in which the traffic buffer of a UE is zero
Event in which the traffic buffer of a UE is a threshold TH1_21 or
more
Event in which the traffic buffer of a UE is a threshold TH2_21 or
more
(Full buffer>TH2_21>TH1_21>0)
(2-2) (Legacy RAT) event in which a traffic buffer for each UE of a
BS is zero
(Legacy RAT) event in which a traffic buffer capacity for each UE
of a BS is TH1_22 or more
(Legacy RAT) event in which a traffic buffer capacity for each UE
of a BS is TH2_22 or more
(Full buffer>TH2_22>TH1_22>0)
(2-3) (New RAT) event in which a traffic buffer capacity for each
UE of a BS is zero
(New RAT) event in which a traffic buffer capacity for each UE of a
BS is TH3_23 or more
(New RAT) event in which a traffic buffer capacity for each UE of a
BS is TH4_23 or more
(Full buffer>TH4_23>TH3_23>0)
Third, an event based on required QoS information may be
configured. In accordance with the present embodiment, the
triggering event based on required QoS information may operate
based on QoS requirements of a service generated by a UE or server
(BS), and the service may operate based on traffic/Bearer/logical
CH/RAN Slice (PHY/MAC Resource/Configuration combination) and a
combination of them. The triggering event based on required QoS
information is divided and described below.
(3-1) Required QoS is a Link Data rate, and
Event in which a required data rate is a threshold TH1_31 or
more
Event in which a required data rate is a threshold TH2_31 or
more
(TH2_31>TH1_31>0)
(3-2) Required QoS is Latency, and
Event in which required latency is a threshold TH1_32 or less
Event in which required latency is a threshold TH2_32 or less
(TH2_32>TH1_32>0)
(3-3) Required QoS is Mobility support, and
Event in which UE mobility speed is a threshold TH1_33 or more
Event in which a required radio link failure (RLF) is a threshold
TH2_33 or less
Event in which required HO latency is a threshold TH3_33 or
less.
Fourth, a triggering event based on a recent traffic transmission
and reception time may be configured as the event of each of the
subframe time of a physical downlink control channel (PDCCH)
recently received by a UE/BS, the time when a UE buffer is zero,
and the time when a buffer for each UE of a (Legacy and/or New RAT)
BS is zero or a combination of two or more of them. In the present
embodiment, the triggering event includes a criterion time and a
given time lapse after the criterion time.
(4-1) Event after a lapse of a threshold time or more since the
time when a UE buffer is zero
Event in which a threshold TH1_41 or more
Event in which a threshold TH2_41 or more
(TH2_41>TH1_41>0)
(4-2) (Legacy RAT) event after a lapse of a threshold time or more
after a traffic buffer for each UE of a BS is zero
Event in which a threshold TH1_42 or more
Event in which a threshold TH2_42 or more
(TH2_42>TH1_42>0)
(4-3) (New RAT) event after a lapse of a threshold time or more
after a traffic buffer capacity for each UE of a BS is zero
Event in which a threshold TH1_43 or more
Event in which a threshold TH2_43 or more
(TH2_43>TH1_43>0)
FIG. 6 shows operation mode change triggering events (cell
coverage, a buffer state, based on required QoS information and a
lapse time from the recent traffic arrival time) of a UE according
to the aforementioned several conditions, operations for a 5G cell
of a UE according to a combination of them, and operations of the
connection state to switch and make transition.
In one embodiment of the operation, as in FIG. 6, the 5G cell modem
operation of a UE may include remaining in a 5G cell modem OFF
state in the aforementioned mode 1 upon initial access, making
transition to a 5G cell discovery state based on a 5G cell coverage
event (mode 2), then making transition to a 5G cell measurement
mode based on a combination of a buffer size-based event (TH1_2x)
or/and a (TR1_3x) required QoS information-based event TH1 (mode
3), and making transition to a 5G cell channel detailed measurement
or continuous active mode based on a combination of a buffer
size-based event (TH2_2x) and/or a (TR2_3x) required QoS
information-based event TH1 (mode 4).
FIG. 7 is an RRC connection management method for low energy of a
UE according to an embodiment of the present disclosure and is a
diagram illustrating an example of a control signaling flow and a
BS/UE modem operation process for a multi-RAT (4G, 5G) low energy
operation in an LTE-5G Tight Integration operation environment.
First, in the state in which the 5G modem of a UE has been turned
off (S760), an indicator indicative of information about 5G
coverage is delivered from a BS supporting the 4G connection of the
UE to the UE (S705). The UE receives a parameter for configuring a
short CP tail while performing a 5G discovery procedure. Such a
parameter related to the CP tail may be a parameter for
differentially configuring and operating 4G/5G C-DRX standby
intervals as described above.
Next, the UE performs a beam training procedure (S710) through a
measurement process for a 5G cell through a 5G discovery procedure
(S765), and feeds information about the scanned best beam to the 5G
BS (S715). In this case, a triggering event for enabling the UE to
initiate the 5G discovery procedure may be generated based on the
capacity of the buffer of the BS (S720). When the 5G discovery
procedure of the UE is completed, the 4G BS indicates 5G cell
addition with respect to the UE (S725). A connection between the 5G
BS, that is, a cell of a mmW band, and the UE is established
(S770). The UE exchanges data through the connection with the 5G BS
(S730). In a C-DRX operation process, when the short CP tail
configured with respect to the 5G connection expires (S735), the
connection with the 5G cell is released (S740), and the UE operates
in the 5G discovery state (S775). Meanwhile, when a CP tail for the
4G connection of the UE also expires (S745), the UE releases the
connection with the 4G BS (S750) and operates in the RRC idle mode
in which the UE waits for paging from the 4G BS (S755).
In the aforementioned process, the buffer capacity threshold TH1 of
the triggering event for enabling the UE to initiate 5G cell
measurement and the buffer capacity threshold TH2 of a triggering
event for a measurement report (MR) for enabling the UE to report
measurement results to the BS may be differently configured. In the
situation in which UE UL transmission is necessary, when a UE/BS
RLC buffer is the threshold TH2 or more, an operation of
transmitting a measurement report (MR) is performed. This is an
operation of consuming UE UL transmission power. Since a MeNB, that
is, 4G LTE, determines cell addition, a UE performs only an
operation of performing measurement and transmitting a measurement
report (MR).
An operation in the LTE-5G tight integration environment, that is,
in the NSA environment, has been described above. An operation in
the LTE-5G independent environment (i.e., SA environment) is
described from FIG. 8.
FIG. 8 is a diagram showing an example of the connection state of a
control plane (CP) and user plane (UP) between a core network and a
BS in an LTE-5G Independent environment based on a multi-link (ML)
in a communication system according to an embodiment of the present
disclosure. In such an environment, an LTE BS and a 5G (NR) BS
independently operate. Such a case may include all of a case where
4G and 5G core networks are separately present, but an interface is
present between them, a case where 4G and 5G core networks are
separately present, but an interface is not present between them,
and a case where a 4G core network evolves and merges with a 5G
core network. Since the LTE BS and the 5G (NR) BS independently
operate, to connect both a control plane (CP) and user plane (UP)
between a UE and a BS in the case of a 4G (LTE) link and to connect
both a control plane (CP) and user plane (UP) between a UE and a BS
in the case of 5G (NR) may be considered.
FIG. 9 is a diagram showing an example of a connection state
between BSs and signaling between protocol layers in an LTE-5G
Independent environment (multi-link (ML)) according to an
embodiment of the present disclosure. In such an environment, since
an LTE BS and a 5G (NR) BS independently operate, 4G and 5G
protocol layers may operate as independent protocol layers with
respect to the RRC, PDCP, RLC, MAC and PHY layers.
FIG. 10 is a diagram illustrating a state diagram for a multi-RAT
(4G, 5G) low energy operation in an LTE-5G Independent operation
environment according to an embodiment of the present
disclosure.
In the LTE-5G independent operation environment, 4G and 5G
connections are independently controlled (including paging). Such a
control operation includes a paging RAT selection process based on
cell coverage wherein a UE is placed. Furthermore, in the LTE-5G
independent operation environment, a gateway stage may support a
flow aggregation. In each of 4G/5G connections, an operation of
determining whether traffic/coverage/QoS support for a UE is
necessary, determining whether a multi-link will be turned on
(1020) or a single link (5G only or 4G only) will be turned on
(1010, 1030) based on a result of the determination, and applying a
result of the determination may be performed.
Such a process may operate based on coverage of a cell where a UE
is placed. Specifically, a determination operation based on each
criterion and combination may be performed based on a 4G cell/5G
cell received signal level or coverage-related indication from a
network. Alternatively, such a process may operate based on the
type of high quality traffic (e.g., VoIP or a new URLLC service)
that may be supported for a UE or a determination operation based
on a buffer state within a BS/UE may be performed based on a QoS
condition.
FIG. 11 is a diagram illustrating an example of a UE modem
operation for each state according to an operation scenario for a
multi-RAT (4G, 5G) low energy operation in an LTE-5G Independent
operation environment according to an embodiment of the present
disclosure.
An RRC state operation of a multi-RAT capable UE may include the
following four states.
(ST1: state 1) Legacy RAT RRC_Connected/New RAT RRC_Idle
(ST2) Legacy RAT RRC_Connected/New RAT RRC_Connected
(ST3) Legacy RAT RRC_Idle/New RAT RRC_Connected
(ST4) Legacy RAT RRC_Idle/New RAT RRC_Idle
In this case, the RRC connected state is divided into a continuous
reception mode and a C-DRX mode. The RRC_Idle state is subdivided
into an Idle DRX (paging) step and an inactive mode in which all of
modem circuits are turned off.
A multi-RAT capable UE operating in the four different states may
operate based on the condition of each of an event (TRiggering
event 1 (TR1): event 1) depending on new RAT (5G) cell coverage, an
event (TR2) according to a buffer condition (buffer size), an event
(TR3) depending on whether high QoS traffic is present, and an
event (TR4) based on required QoS information or a combination of
two or more of them. Such a multi-RAT capable UE may operate as
follows while changing the aforementioned RRC state in response to
the event according to the aforementioned several conditions.
In the LTE-5G (MN-SN) independent, that is, the SA environment,
after a 5G discovery process is terminated, an operation for a UE
to determine a 5G modem turn-on time (5G ON time determination)
includes an operation of determining a 5G modem turn-on time based
on mobility support (performance requirements for a handover
failure, handover latency and a radio link failure) according to UE
mobility speed. In one embodiment, when UE moving speed is high
speed and thus a threshold (e.g., 120 km/h) or more and a handover
latency requirement is a threshold (e.g., 1 second or 0) or less,
the operation is performed using an MN link, and includes an
operation of performing data transmission without turning on an SN
or using a continuously turned-on SN without turning off the SN.
Furthermore, the operation includes an operation of performing
mobility support of a UE through a continuously turned-on MN
without turning off the MN.
(ST1) Legacy RAT RRC_Connected/New RAT RRC_Idle: when a case where
a buffer size is a TR2-based threshold or more or required QoS is a
threshold (Data rate, latency requirements) TR3 or more is
satisfied, a 5G cell is turned on and operates as an ST2
(ST2) Legacy RAT RRC_Connected/New RAT RRC_Connected: when required
QoS is a (mobility requirements, UE mobility speed) threshold or
less or satisfies at least one in response to the event depending
on 5G coverage (TR1) in a 5G-centered coverage area condition
(TR3), a 4G cell is turned on and operates as an ST3
(ST3) Legacy RAT RRC_Idle/New RAT RRC_Idle: if time of a threshold
or more elapses in response to the event based on the recent
traffic transmission and reception time, a 5G cell and a 4G cell
are turned on and operate as an ST4
(ST4) Legacy RAT RRC_Idle/New RAT RRC_Idle: since multi-RAT capable
UE paging can support both the two RATs, a multi-RAT UE selectively
receives one of the New RAT and the Legacy RAT and operates.
In the LTE-5G interworking, NSA environment, a UE has operated to
receive LTE (4G) paging in the RRC idle state. In contrast, in the
LTE-5G independent, SA environment, a UE may operate to receive
paging based on a recent RAT that has been recently turned on. That
is, a multi-RAT capable UE may operate to randomly select one of
the two RATs and to receive a paging message and may operate to
select an RAT whose connection has been terminated most recently
and to receive a paging message.
According to the aforementioned embodiment, an operation of
controlling the RRC connected state to a minimum in a 5G cell of a
multi-RAT capable UE may also be applied to the SA environment.
That is, RRC state connection control of a multi-RAT capable UE may
include a process of operating a CP tail for a new RAT (NR)
relatively shorter than a CP tail for the legacy RAT. In accordance
with one embodiment, RRC state connection control of a multi-RAT
capable UE may include an operation of designing the CP tail for
the new RAT close to zero (0)+margin (margin <<1) and
immediately making transition to the RRC idle state right after NR
traffic is transmitted and received.
In this case, regarding whether a paging reception or non-reception
idle state for the NR will operate, whether a paging association
operation will be performed is determined depending on the LTE-5G
interworking environment and the LTE-5G independent environment.
Information related to the paging association operation may be
delivered to a multi-RAT UE using a method for a core network, such
as an ANDSF or MME, to notify the multi-RAT UE of the information
through a legacy RAT or new RAT BS when the UE first accesses an
N/W.
Criterion conditions for reducing/expanding the RRC state are
described below. First, embodiments for reducing an RRC connection
are described. In order to stop the RRC connected state of a
corresponding 5G cell earlier than an initially configured timer
and to change a UE into to an idle mode or a mode in which paging
is not received, a 5G BS/UE may perform at least one of:
(ST1) an operation of immediately transmitting the RRC release
message of a BS,
(ST2) an operation of transmitting a fast dormancy request message
of a UE
(ST3) an operation of transmitting a power preference indicator
(PPI) message of a UE
Conversely, embodiments in which an RRC connection is delayed are
described. In order to additionally minimize N/W signaling overhead
and power consumption of a UE occurring due to frequent transition
from the idle state to the connected state although the UE enters
an early Idle state attributable to a reduction in the CP tail by
expanding the RRC connected state of a corresponding 5G cell
greater than an initially configured timer, a 5G BS/UE may perform
at least one of:
(SUS1) an operation of delaying the transmission of a BS RRC
release message;
(SUS2) an operation of transmitting a UE new RRC Suspend request
message; and
(SUS3) a timer extension operation through UE dummy data
transmission.
The embodiment in which DRX and inactivity timer sets for HF and LF
cells in the SA environment, among the aforementioned embodiments,
are differentiated, configured and operated may also include a
method for a BS to configure a corresponding parameter as a fixed
value and operate it.
Another embodiment may also include an operation of determining and
configuring parameters related to DRX and an inactivity timer based
on each of the requirements for whether coverage of a secondary
node (SN) BS is included, service information of traffic and QoS
required by a service, the amount of data for traffic, the state
(amount) of a buffer accumulated in a UE/BS, mobility speed of a
UE, and mobility support, and a combination of two or more of them
is also possible. That is, an event trigger, defined based on each
of conditions based on the cases where a UE is in coverage of a
secondary node (SN) BS, service information of traffic and QoS
required by a service are low latency or a high capacity, the
amount of data for traffic and a buffer capacity accumulated in a
UE/MN or an SN BS is a threshold or more, and in the case of
mobility support (handover and radio link failure performance
requirements) according to UE mobility speed and defined based on a
combination of a plurality of the conditions, may be configured and
applied.
Furthermore, an embodiment in which the values of a C-DRX parameter
and user inactivity timer for an SN link are conservatively
determined and set based on the aforementioned contents may also be
taken into consideration. An embodiment in which the values of a
C-DRX parameter and user inactivity timer for an MN link are
conservatively determined and set may also be taken into
consideration. In this case, the meaning that the values are
conservatively determined and set may mean a method of setting the
user inactivity timer relatively long, a method of setting
drx-Config and drx-InactivityTimer, that is, sub-parameters of
C-DRX, relatively long, a method of setting drx-RetransmissionTimer
relatively long, or a method of setting drxShortCycleTimer
relatively long.
FIG. 12 is a diagram illustrating an example of a control signaling
flow and a BS/UE modem operation process for a multi-RAT (4G, 5G)
low energy operation in an LTE-5G Independent operation environment
according to an embodiment of the present disclosure.
First, in the state in which the 5G modem of the UE has been turned
off and only the 4G modem has been turned on (S1260), a paging
message is delivered from a BS, supporting the 4G connection of the
UE, to the UE (S1200). When the UE recognizes a necessity to turn
on a 5G connection in response to a triggering event (S1205) to
compare the capacity of a buffer with a given threshold TH1, the UE
performs a 5G discovery procedure (S1265) and performs a
beamforming random access channel (RACH) procedure on a BS
supporting a 5G connection (S1210).
When a connection between the UE and the 5G BS is established and a
triggering event (S1215) is satisfied by comparing the capacity of
the buffer of the UE with another threshold TH2, the UE adds a 5G
cell and exchanges data through the connection with the 5G BS
(S1220, S1225). In such a process, only the 5G connection of the UE
is activated and the 4G modem may operate in the RRC idle state
(S1270). Meanwhile, after data transmission through the 5G
connection of the UE is completed, when a given time elapses
(S1230), the 5G modem of the UE is turned off through a 5G cell
release process of the UE (S1235). Such a time may be a time
interval corresponding to the aforementioned short CP tail.
The 4G connection of the UE is the RRC idle state, and the UE
receives a 5G paging message (S1240) in the 5G discovery state
(S1275). When the time interval for the 4G connection expires
(S1245), the connection with the 4G cell of the UE is also released
(S1250). The UE operates in the state in which a 4G paging message
is received (S1255).
For an efficient 5G radio tail (user inactivity timer) interval
reduction operation according to an embodiment of the present
disclosure, a UE connection standby time reduction operation based
on a traffic end point (TCP flag FIN) is described below. FIG. 13
shows an example of a UE connection standby time reduction
operation based on a traffic end point (TCP flag FIN) for an
efficient 5G radio tail (user inactivity timer) interval reduction
operation according to an embodiment of the present disclosure.
This drawing shows the final (FIN) indication of a TCP packet from
a transmission stage and a reception stage and ACK transmission for
identifying the final indication.
The TCP is a protocol of a transmission layer. The TCP splits data
received from a data stream and generates a TCP segment by adding a
TCP header. The TCP enables the exchange of data between network
nodes to be performed stably without an error. When a transmission
node sets the FIN flag of flags 1410, included in a TCP header, to
1 bit and performs transmission, this means that there is no data
to be transmitted by the transmission side, that is, the last of
transmission. A reception node that has received the FIN flag set
to 1 sets an ACK flag to 1 bit and transmits it as a response
thereto.
FIG. 14 is a basis technology for showing an example of a UE
connection standby time reduction operation based on a traffic end
point (TCP flag FIN) for an efficient 5G radio tail (user
inactivity timer) interval reduction operation according to an
embodiment of the present disclosure, and is a diagram including
FIN indicative of the last of transmission as the type of flag
marked in a TCP header.
FIG. 15 is a basis technology for showing an example of a UE
connection standby time reduction operation based on a traffic end
point (TCP flag FIN) for an efficient 5G radio tail (user
inactivity timer) interval reduction operation according to an
embodiment of the present disclosure, and is a diagram showing a
hierarchical structure and unit in a wireless communication
protocol.
A TCP-related embodiment is described specifically. A UE inactivity
timer (CP tail) for a 5G cell according to the aforementioned
embodiment may be configured based on several criteria. For
example, in accordance with a first criterion, the UE inactivity
timer (CP tail) may be configured based on a traffic end point (TCP
flag FIN). When a FIN value, that is, one of the TCP header flags
(6 bits), is received, the UE inactivity timer (CP tail) may be
configured to early terminate a connection or may be configured to
maintain a connection until an ACK flag value is received as a
response to the FIN flag. Furthermore, the UE inactivity timer (CP
tail) may be configured and operated to extend a connection based
on an SYN value, that is, a different flag value of the TCP Header
flags (6 bits).
In order to identify such a TCP flag of IP (TCP) traffic,
information of the corresponding flag may be identified by
performing TCP header parsing on IP (TCP) traffic Header
information implemented in the AP of a UE when a PDCP implemented
in a UE CP is generated. When a total number of TCP connections of
a plurality of TPC connections is 0, the UE operates to transmit UE
feedback, for example, a power preference indicator (PPI) so that a
BS reduces a radio tail (CP tail) (i.e., perform RRC release).
In this case, the UE and the BS may perform a PPI determination
operation based on the number of TPC connections through IP (TCP)
flag parsing in order to manage the total number of TCP connections
of the plurality of TPC connections. The UE and the BS perform the
aforementioned operation for RRC release when the total number of
TCP connections is 0 through a number increase (++) operation based
on a TCP connection request (SYN) flag and a number reduction (--)
based on a TCP connection termination (FIN) flag.
As another method, a BS may identify information of a corresponding
flag by performing TCP header parsing. In this case, a method of
performing a radio tail reduction operation by performing the RRC
release of the BS without UE feedback transmission is also
possible.
An embodiment if a CP tail is reduced and the 5G connection of a UE
needs to be extended while minimizing the 5G connection of the UE
according to the aforementioned embodiment is described below. In
an operation for a UE to feed information regarding whether a data
request from a server has been made back to a BS and to use CP tail
control, a method of extending a CP tail by notifying the UE that
download traffic (e.g., advance and receive Email confirmation and
push service) has been scheduled in the server after the UL traffic
transmission request is described. For example, i) whether DL data
has been transmitted after corresponding UL data, ii) whether
ACK/NACK reception is necessary, iii) Keep alive message dedicated,
and iv) whether the server has been updated (involving DL
transmission) may become conditions for extending the 5G connection
of a UE. A combination of two or more of the conditions is also
possible. The BS may use information indicative of such criteria by
incorporating them in a DRX period and radio tail coordination
process.
Conversely, in a method of transmitting whether DL traffic has
occurred as a server operation according to a request (UL) from a
UE, i) a method of marking in a buffer status report (BSR) new
field as a method of marking in a new field of the existing MAC
control element or ii) an operation of marking in an UL data MAC
header and transmission may be performed based on new/existing
control signaling.
FIG. 16 is a diagram showing an example of an operation based on DL
traffic occurrence as a server operation according to a UE request
(UL) for a 5G CP tail interval minimization control operation
according to an embodiment of the present disclosure.
There is a need for a new/existing control signaling design because
a data request from a UE needs to be transmitted to a BS through
feedback. After the transmission of a scheduling request (SR) and
buffer status report (BSR) from a UE, when an uplink grant is
received from a BS (S1610, S1620, S1630, S1640), the UE transmits
UL data and simultaneously requests DL traffic transmission
(S1650). In response thereto, the BS transmits downlink data to the
UE (S1660). Such transmission and reception process of the UE and
the BS may operate according to i) a method of marking in a new
field of the existing MAC control element, for example, a method of
marking a data request from the UE in a buffer status report (BSR)
new field or ii) a method of marking in an UL data MAC header. As
described above, since piggyback on the existing signal is
performed or a new field is added, information about each of
whether DL data has been transmitted after corresponding UL data of
a UE, a criterion regarding whether ACK/NACK reception is
necessary, Keep alive message dedicated, and whether a server has
been updated (involving DL transmission) and a combination of two
or more of them may be transmitted to a BS. Accordingly, the BS may
control a C-DRX and idle DRX period for a corresponding link and a
standby time (radio tail) from the last transmission and reception
traffic based on the received information, may configure the C-DRX
and idle DRX period and the standby time (radio tail), and may
control the UE by applying them.
FIG. 17 is a diagram showing an example of an operation based on DL
traffic occurrence as a server operation based on the cost of a
process for a UE to make transition from the RRC_Idle state to the
RRC connected state for the purpose of a 5G CP Tail interval
minimization control operation according to an embodiment of the
present disclosure.
If a short tail is configured and operated based on an operation
based on the cost of an RRC state transition process of a UE,
problems of an increase in signaling load when traffic prediction
is impossible and QoE deterioration may occur. Such problems may
result in, specifically, i) a burden of UE request transmission and
BS connection release configuration, ii) power consumption
attributable to UE uplink transmission and control resource
consumption when multiple UE operations are performed, iii) a
burden of a connection reconfiguration after entry into the idle
state when the prediction of a traffic pattern is impossible, and
iv) LTE UE-based transmission power consumption (523 mW) and
latency occurrence (1.4 second: paging latency 1.28 second, and
connection reconfiguration 84 ms latency expected).
In order to supplement such problems, an RRC inactive (1720) state
(or light connection) in which a procedure consumed when a UE makes
transition to the RRC connected state has been minimized may be
introduced, instead of immediately entering an RRC idle (1730)
state when an RRC connection in an RRC Connected (1710) state is
released. Such an RRC inactive state is different in that an RRC
connection is not fully released, but is deactivated, unlike the
RRC idle state. In this case, a 5G Tail interval minimization
operation needs to be designed by taking into consideration a case
where the RRC inactive state makes transition to the RRC connected
state again. More specifically, the promotion cost (transition to
the RRC connected state) of a UE is changed depending on whether a
corresponding network operates in legacy idle or in the RRC
inactive state after the RRC connected state. A method operating
based on i) a latency occurrence time attributable to N/W signaling
overhead and ii) BS power consumption of a UE for a corresponding
procedure may be implemented as an operation of controlling a CP
tail by incorporating such a cost. Meanwhile, instead of
introducing the RRC inactive state according to the aforementioned
embodiment, an RRC suspend state (ECM Connected state) in which a
network, such as a BS, retains context of a UE may be introduced.
Transition to the RRC connected state is made through a procedure
resumed in the RRC suspend state.
In accordance with one embodiment, in a warming up procedure, that
is, an operation necessary prior to wake up (upon on operation)
data reception in sleep during a DRX operation, a C-DRX and idle
DRX period and a standby time (radio tail) from the last
transmission and reception traffic may be controlled by taking into
consideration a beamforming synchronization operation, switching on
hardware circuit including precise-clock, an RF circuit with
massive antennas, and an additional high speed core processor, and
they may be signaled.
In accordance with the present embodiment, since a promotion cost
varies depending on a UE implementation and network configuration,
information related to a promotion time and promotion energy may be
added to UE category information, and a network may transmit the UE
category information to a BS. The BS may perform RRC release based
on the received UE category information.
Furthermore, a minimum idle interval (i.e., the time maintained to
a minimum when making transition to RRC Idle) may be determined
based on such promotion cost-related information, and transition to
the RRC connected state may be delayed. Accordingly, a power
reduction effect of a UE when the UE enters the idle mode can be
guaranteed because the minimum idle interval maintained to a
minimum when the UE makes transition to RRC Idle is applied.
In accordance with another embodiment, as a method of configuring a
CP tail based on 5G coverage triggering, if there is no possibility
that a UE will be out of 5G coverage or in 5G coverage, an NR CP
tail may be set to zero (if there is no possibility that the will
be out of 5G coverage) or paging disable (if there is no
possibility that the will be in 5G coverage) may operate. In the
present embodiment, the method may operate based on
Tight-Interworking within a multi-RAT UE or information from a
multi-link or legacy RAT BS.
In accordance with another embodiment, in a method of configuring a
CP tail based on a UE/BS buffer, as one embodiment of an operation
of controlling a radio tail based on a UE/BS buffer, an operation
of early executing RRC Release when there is no data in an UL PDCP
buffer and when there is no data in a BS DL PDCP buffer is also
possible in addition to an operation of delaying PPI transmission
when data is present in a UE UL PDCP buffer and an operation of
delaying RRC Release when data is present in the BS DL PDCP
buffer.
FIG. 18 is a diagram showing the configuration of a UE according to
an embodiment of the present disclosure. Referring to FIG. 18, the
UE may include a transceiver unit 1810, a UE controller 1820, and a
storage unit 1830. In the present disclosure, the UE controller
1820 may be defined as a circuit- or application-specific
integrated circuit or at least one processor.
The transceiver unit 1810 transmits and receives signals to and
from a different network entity. The transceiver unit 1810 may
receive system information from a network entity (e.g., a CU, a DU
and/or a BS), for example, and may receive a synchronization signal
or a reference signal. The transceiver unit 1810 may be implemented
in the form of an RF unit including a modem.
The UE controller 1820 may control an overall operation of the UE
according to the embodiments proposed in the present disclosure.
For example, the UE controller 1820 may control the transceiver
unit 1810 and the storage unit 1830 to perform operations according
to the embodiments described in the drawings. Specifically, the UE
controller 1820 may differently configure the UE inactivity timer
for each RAT or may differently turn on/off the modem included in
the transceiver unit 1810 for each RAT according to an embodiment
of the present disclosure.
The storage unit 1830 may store at least of information transmitted
and received through the transceiver unit 1810 and information
generated through the UE controller 1820. For example, the storage
unit 1830 may store UE inactivity timer-related information
received through the transceiver unit 1810.
FIG. 19 is a diagram showing the configuration of a BS according to
an embodiment of the present disclosure. Referring to FIG. 19, the
BS may include a transceiver unit 1910, a BS controller 1920, and a
storage unit 1930. In the present disclosure, the BS controller
1920 may be defined as a circuit- or application-specific
integrated circuit or at least one processor.
The transceiver unit 1910 may transmit and receive signals to and
from a different network entity. The transceiver unit 1910 may
transmit system information to a UE, for example, and may transmit
a synchronization signal or a reference signal. The transceiver
unit 1910 may be implemented in the form of an RF unit including a
modem.
The BS controller 1920 may control an overall operation of the BS
according to the embodiments proposed in the present disclosure.
For example, the BS controller 1920 may control the transceiver
unit 1910 and the storage unit 1930 to perform operations according
to the embodiments described in the drawings. Specifically, the BS
controller 1920 may establish or release an RRC connection with a
UE according to an embodiment of the present disclosure.
The storage unit 1930 may store at least one of information
transmitted and received through the transceiver unit 1910 and
information generated through the BS controller 1920. For example,
the storage unit 1930 of a CU/DU may store information or a value
related to the UE inactivity timer, that is, a standby time in
order to release an RRC connection with a UE.
Meanwhile, the preferred embodiments of the present disclosure have
been disclosed in this specification and drawings. Although
specific terms have been used, they are used in common meanings in
order to easily describe the technical contents of the present
disclosure and to help understanding of the present disclosure, but
are not intended to limit the scope of the present disclosure. It
is evident to a person having ordinary skill in the art to which
the present disclosure pertains that other modified examples based
on the technical spirit of the present disclosure are possible in
addition to the disclosed embodiments.
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